Shares of

Rita Medical Systems

( RITA) were among the worst-performing health-related stocks Friday, tumbling 18% after the medical device maker posted a wider-than-expected fourth-quarter loss and said it would also be in the red during the first quarter.

The company reported a loss of $7.2 million, or 17 cents a share, on sales of $12.1 million. On a so-called pro forma basis, which excludes items, the company posted a loss of $1.1 million, or 3 cents a share. Analysts polled by Thomson First Call expected a pro forma loss of a penny a share on sales of $11.9 million. During the year-earlier period, the company recorded a pro forma loss of $1.3 million, or 3 cents a share, on sales of $11 million.

Looking ahead, Rita Medical projects a first-quarter pro forma loss of $700,000 to $1.2 million on sales of $12 million to $12.5 million. Analysts project break-even earnings and sales of $12.5 million. For all of 2006, the company sees a pro forma results ranging from break-even to a loss of $1.5 million. Shares were trading down 75 cents to $3.47.

Viasys Healthcare

( VAS) rose 6% after the maker of medical products posted better-than-expected fourth-quarter results and reiterated its 2006 guidance. The company posted adjusted earnings from continuing operations of $12.7 million, or 39 cents a share, on sales of $155.2 million. Analysts expected earnings of 38 cents a share and sales of about $141 million. During the year-earlier period, the company reported adjusted earnings from continuing operations of $8.7 million, or 28 cents a share, on sales of $110.7 million.

Viasys continues to forecast 2006 earnings of $1.25 to $1.30 a share, excluding stock-based compensation costs. Analysts project earnings of $1.30 a share. Shares were trading up $1.60 to $29.76.

Shares of

Nabi Pharmaceuticals

(NABI)

fell 9% after the biotechnology company posted a wider fourth-quarter loss, with lower-than-expected sales. The company reported a loss of $75.6 million, or $1.25 a share. The results included a $20.1 million income tax provision and a $19.8 million impairment charge related to a vaccine facility. Analysts expected a loss of 25 cents a share. A year earlier, the company recorded a loss of $17.1 million, or 29 cents a share, with a $434,000 tax benefit. Fourth-quarter sales, meanwhile, fell to $25.3 million from $41.7 million, missing Wall Street's expectation of $35.5 million. Nabi shares were down 36 cents to $3.82.

Salix Pharmaceuticals

(SLXP)

fell 6% after the drugmaker's fourth-quarter adjusted earnings came in below Wall Street's forecast. The company reported a loss of $2.9 million, or 6 cents a share. Excluding items, Salix earned $6.6 million, or 17 cents a share, below analysts' target of 22 cents a share. The company posted sales of $50.9 million, compared with analysts' average estimate of $47.6 million. A year earlier, the company earned $3.6 million, or 9 cents a share, on sales of $28.9 million.

For the first quarter, Salix expects sales of $43 million, below analysts' estimates of $46.2 million. For all of 2006, the company sees sales of at least $205 million, ahead of analysts' projections of $203.9 million. Shares were trading down $1.09 to $16.43.

Shares of

Endologix

(ELGX) - Get Report

slumped 18% after the medical device maker posted weaker-than-expected fourth-quarter results. The company reported a loss of $5.7 million, or 16 cents a share, on sales of $2 million. Analysts expected a smaller loss of 10 cents a share and sales of $3.3 million. The company's year-earlier loss totaled $3.3 million, or 10 cents a share, on sales of $852,000. Shares were trading at $5.06, down $1.13.

Other health care volume movers included

Pfizer

(PFE) - Get Report

, up 13 cents to $26.27;

Johnson & Johnson

(JNJ) - Get Report

, down 55 cents to $57.71;

Merck

(MRK) - Get Report

, down 33 cents to $35.08;

Amgen

(AMGN) - Get Report

, down 19 cents to $74.50;

Boston Scientific

(BSX) - Get Report

, up 1 cent to $24.21;

Elan

(ELN)

, up 5 cents to $14.22;

Bristol-Myers Squibb

(BMY) - Get Report

, down 28 cents to $22.92; and

Schering-Plough

( SGP), down 12 cents to $18.85.